Z's line "I was going to include you in my erotic fantasies" was originally "I was going to include you in my most erotic sexual fantasies", but was shortened to retain a PG rating. In the German dubbed version the "sexual" is included. The line was from a spider sketch called "What Causes Homosexuality?" which was cut from Allen's Every Thing You Always Wanted to Know About Sex * But Were Afraid to Ask. Woody Allen was going to use that line as Louise Lasser was about to eat him - the sketch was never used because Allen couldn't think of a way to end the scene. Since the sketch was not used, the writers got a hold of the line and, realizing the irony (spiders, ants), had Allen's character (Z) state it.
Arnold Schwarzenegger was originally offered the part of Weaver. When Schwarzenegger wanted to be paid for the role, it went to Sylvester Stallone who was willing to do it for free.
One of two animated films that Danny Glover would appear in for Dreamworks. The other is The Prince of Egypt which came out one month after this film was released.
In the original development, the ants had six limbs, some of them wore clothes, gloves, and lightbulbs appeared whenever they had an idea. None of these made it into the finished film. Also, General Mandible looked more visibly sinister in early drafts, but they toned it down for the final result.
John Mahoney plays one of the ants in the film. In a peculiar coincidence, David Hyde Pierce, Mahoney's co-star on Frasier played an insect in Pixar's A Bug's Life, a similar film about an ant colony, both in the same year.
Apparently Woody Allen nailed every reading he did for Z. But he also got very physical in the recordings, ruining some of the takes because the animators couldn't keep up with him.
Bala was a lot nastier in the early days of defining the character. Sharon Stone's reading helped to change that by balancing sass with spoiled, without ever becoming too bratty.
Christopher Walken's voicework was so excellent that Cutter's role was expanded. He was originally a faceless lackey to General Mandible, but Walken brought some unexpected depths to the character.
Woody Allen felt uncomfortable watching Z because he was reminded so much of himself. This is why he can never watch any of the films he makes that he has a role in.
Although there are humans in the film, we never see any faces. This may have been because DreamWorks didn't want to incur the same criticisms that Pixar received when Toy Story came out. The humans in the film looked grotesque and not at all plausible, because they hadn't perfected a computer animated human face yet.
A reason why the movie has a PG rating is because of casual swearing, an unusual thing to hear in an animated film. This is often omitted whenever the film is shown on TV.